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  1. #include <functional>
  2. #include <iterator>
  3. #include <vector>
  4. #include <utility>
  5. #include <algorithm>
  6. #include <iostream>
  7. #include <typeinfo>
  8. #include <array>
  9.  
  10. std::vector<std::pair<std::function<void(int)>, void*>> callbacks;
  11.  
  12. class MyClass{
  13.   static unsigned const num_possible_callbacks = 2; // keep updated
  14.   std::array<std::type_info const*, num_possible_callbacks> _infos;
  15.   unsigned _next_info;
  16.  
  17.   // adds type_info and passes through
  18.   template<class T>
  19.   T const& add_info(T const& bound){
  20.     if(_next_info == num_possible_callbacks)
  21.       throw "oh shi...!"; // something went out of sync
  22.     _infos[_next_info++] = &typeid(T);
  23.     return bound;
  24.   }
  25. public:
  26.   MyClass() : _next_info(0){
  27.     using std::placeholders::_1;
  28.     callbacks.push_back(std::make_pair(
  29.         add_info(std::bind(&MyClass::myFunc, this, _1)),
  30.         (void*)this));
  31.     callbacks.push_back(std::make_pair(
  32.         add_info([this](int i){ return myOtherFunc(i, 0.5); }),
  33.         (void*)this));
  34.   }
  35.  
  36.   ~MyClass(){
  37.     using std::placeholders::_1;
  38.  
  39.     callbacks.erase(std::remove_if(callbacks.begin(), callbacks.end(),
  40.         [&](std::pair<std::function<void(int)>, void*> const& p) -> bool{
  41.           if(p.second != (void*)this)
  42.             return false;
  43.           auto const& f = p.first;
  44.           for(unsigned i = 0; i < _infos.size(); ++i)
  45.             if(_infos[i] == &f.target_type())
  46.               return true;
  47.           return false;
  48.         }), callbacks.end());
  49.   }
  50.  
  51.   void myFunc(int param){ /* ... */ }
  52.   void myOtherFunc(int param1, double param2){ /* ... */ }
  53. };
  54.  
  55. int main(){
  56.   auto print = []{ std::cout << "Callbacks:" << callbacks.size() << "\n"; };
  57.   print();
  58.   {
  59.     MyClass c1;
  60.     print();
  61.     {
  62.       MyClass c2;
  63.       print();
  64.     }
  65.     print();
  66.   }
  67.   print();
  68. }
Success #stdin #stdout 0s 3068KB
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stdin
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Standard input is empty
stdout
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Callbacks:0
Callbacks:2
Callbacks:4
Callbacks:2
Callbacks:0
https://ideone.com/sTLRD
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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